Process for making lasting records



Patented Mar. 28, 1944 2,345,549 PROCESS FOR MAKING LASTING RECORDS Peter S. Christaldl,

Steadman, Nutley,

Upper Montclair, Albert and David T.

ton, N. J., assignors to Allen B. Dn Mont Laboratories, Inc., Passaic, N. 1., a

Delaware corporation of No Drawing. Application October 1c, 1943,

' Serial No. 506,598

This invention relates to a method of making records in which materials that are sensitive to light are used.

In accordance with this invention, figures or designs of diflerent sorts can be quickly recorded so that they will be lasting without employing the steps of photographing, developing, fixing, and washing, as in the ordinary way. Records are made by this invention practically instantaneously and are lasting.

The invention is particularly useful, for example, for recording patterns that are caused to appear by means of an electron beam upon the face of an oscillograph tube, although it can be used for other purposes.

In carrying out the invention, an emulsion of a salt is prepared, which has the property of changing color when exposed to light as a result 01' chemical decomposition. The reaction which causes the change is accelerated when a higher concenlz'ation of ultraviolet light is used. The reaction is also accelerated small amounts of moisture. The emulsion is deposited upon a base or support so that it can be exposed to the pattern or figure or which a record is to be made.

The following is given as a specific example illustrating the invention, from which it will be by the presence oi.-

writing or seen that other salts of which the color is quickly changed by ultraviolet light may be used.

An equeous emulsion of zince cadmium sulphide and manganese is made, using from about one part per thousand to one part per ten thousand of manganese, compared to the zinc cadmium sulphide by weight. Approximately 85% zinc and 15% cadmium are present in the zinc cadmium sulphide. The emulsion used in coating the substrate or base may consist of gelatine. polyvinyl '4Claims. (ores-5y alcohol, methyl cellulose, or any water soluble medium which produces suillcient viscosity to P rmit the formation of an emulsion which will remain constant throughout the mass during application. Said application can be by any conventional method such as applying a layer of uniform thickness by roll-coat, by spreading by a blade, or by spraying'on a substrate or solid base such as wood, metal, glass or film, and is permitted to set. It has a bright yellow color.

Since the presence of moisture is desirable during the process of producing a permanent record, the coated substrate should be exposed to moisture before it is brought into proximity to the source of ultra-violet light, which may, for example, be a pattern on an oscillograph tubemade by an electron beam sweeping across a prepared surface, whereupon the parts exposed to the light from the pattern change quickly in color from bright yellow to gray and remain so for along t e.

the emul- 4. Theprocess ofclaim 1,lnwhichtheexposure N is sufficient to change the color of the exposed part from yellow to gray. I

PETER. S. CHRISTAIDI. ALBERT STEADMAN.

DAVID '1'. WILBER. 

